1. Field of the Invention
The present invention relates to a hub ring having positive engagement, such as toothings that engages a clutch cover to at least partially transmit a torque.
2. Description of the Related Art
As a rule, clutch disks are constructed in such a way that a hub ring fits on a hub by which the torque can be transmitted from the hub ring to the input shaft of the transmission.
The drivetrain provided in a vehicle generates torsional vibrations which can lead to undesirable secondary effects such as chattering, buzzing, or drumming noises. Therefore, particularly in the automotive industry, clutch disks include torsional vibration dampers that prevent these unwanted side effects and to enable smooth starting. Further, predampers have been incorporated in clutch disks. These predampers serve, among other things, as an idling system.
Particularly in clutch disks with predampers, a hub ring fits on a hub which is rotatable relative to the hub ring by a certain angle, the so-called predamper angle. The toothing provided at the inner circumference of the hub ring serves as a stop for the predamper. After the predamper angle is exceeded, this internal toothing serves to transmit the torque from the hub ring to the hub of the input shaft of the transmission. Cover plates which serve to receive the pressure springs of the main torsional vibration damper are arranged at the upper side and lower side of the hub ring. The connection between the hub ring and the cover plates is generally produced by rivets that are guided in bore holes extending through the thickness of the hub ring and through the thickness of the cover plate. The rivets not only fasten the cover plate to the hub ring, but also transfer the torque from the cover plates to the hub ring. In general, the total flow of force in the clutch disk is such that the engine torque is transferred to the cover plate, hub ring and, finally, to the hub and transmission shaft via clutch disk linings, a driver disk and the torsional vibration damper.
The total transfer of torque between the hub and pressure springs of the torsional vibration damper is accordingly carried out in such clutch disks using the rivets which are guided through the cover plate and the hub ring.
This high load requires that a certain number of rivets and a certain diameter of the rivets must be used to prevent the rivets from shearing off. Further, in order to preserve the stability of the hub ring itself, the hub rings must be produced from a material of high strength. As a rule, forged parts are used for this purpose. Further, by providing bore holes suitably sized to receive the rivets, the hub ring is weakened at the hole location. This weakening is countered by reinforcement or strengthening in the direction of the center of the hub ring. This strengthening serves at the same time as an internal toothing for engaging with the external toothing of the hub. Since the number of teeth of the internal toothing of the hub ring is determined by the number of rivets needed to avert shearing, the predamper angle, that is, the play between the internal toothing of the hub ring and the external toothing of the hub, is limited.